Art of lubrication



Patented as. 17, 1936 UNITED, STATES PATENT OFFICE s 2,081,328 I an! 01? LUBRICATION William B.'D. Pen niman, Baltimore, Md.

. 9 Claims. 1 (Cl. 87- -'--9) This invention relates to lubricants, and their withviscosity numbers 01-1 to 18 and ranging utilization, as well as to methods of making such lubricants, f

From a Broad andfgeneral consideration, the I lubrication so! machines and machine elements,

including for example bearings, gears, cylinders, etc., is dependent upon a number of factors including the mechanical construction and speed 10, andiloadon the bearingisurta ces to be lubricated,

' on the supply oi. lubricant, and on the kind and properties of the lubricantsf The present invention is particularly concerned with the kind and properties of lubricants used in lubrication.

5 Consideration of .the nature of the lubricant employed, requires a consideration of the widely varying conditions under which lubricants may be used. Such conditions under which two sur- .faces;pass over one another vary .irom the high speed andhigh temperatures involved in internal combustion engines to the relatively low speed and low temperatures present in swivel plates, for example, of a railroad turntable.

to take atypical case, is dependent up n fi the supply or lubricana'second the viscosity of the lubricant, and third, the"oiliness or the lubri- Clint; I 7

b. The lubricantagenerally employed, are of hyspecify the lubricant in terms of its viscositywhich I was readily determined, thereby more orless loosely fixing the oilin property desired. As aresult in using thes mineral. and related oils, in order to obtain the required degreeof oiliness, it P was necessary to use oils of relatively highwisco'sity. 1, s

The practice in the prior art 15177811 illustrated by referring to standard reference works, such {,0 as that of -T. C. Thomp'son who lists eighteen oils Generally the lubrication of any given bearing tric street failwaysrv in viscosity as follows:

Saybolt seconds 5 ViscosityNos. I '100 1 WP. 212" it,

1 as g" ,3:

95 e0 3,2 9, 125 a4- mo 81 as o 180 so as 240 115 4a a v 350 100 50,

ll 1400 470 to l3 1900 000 H s 105 16 33 11 1400, 20

Under this designation oi oils as given by 1 Thompson in the work referred to, oilswith the viscosity numbers 1 to 5, inclusivegarethe socalled spindle oils. They do not generally enter into the (lubrication program of the prior art, and are not generally considered in such program. Oils in the'range irom viscosity numbers"? to 9, that, is oils having viscosities of from 240 to about 600 Saybolt seconds at 100' F. are the oils gen- Fio;

erally' used in the prior art in connection with, the lubrication oi the :lournals'and axles of 1811.". way rolling stock, such as those of steam and elec- 1A3 rurther illustrating the prior artrellance on 'the use 01 heavy or viscous lubricating oils, reterence may'be made to'the specifications set out in Technical PaperNo. 323A of the Bureau oi! Mines, United States Government, and entitled "United States Government Specifications'ior Lu-. bricantaand Liquid Fuels and Methods of Test ing. on page 28 or this paper, the names and grades offthe various lubricants are set forth, But in this paper, the lightest grade of oil suggested for lubrication is a so-called Class A, Ex-.

tra Light having a viscosity of about at F.; while on page 9 of this paper the whole Class A embracing oils with vi'scosities oiirom 135 to 360" is given as used only for very light machinery. So that'underthese specifications,-

As exemplary of this prior art practice, refer ence may be made to the practice in connection with the lubrication of internal combustion engines, such as those employed in automobiles. It is customary in that art where the speed and load are high, to mix with the lubricating oil, lar'ge percentages of cylinder stock, or other very heavy oils in order to obtain the desired adhesiveness.-, And so much is this the custom in this field that petroleum lubricating oils are generally sold on the basis of their viscosity only, whereby the adhesiveness is inthis way secured to a greater or lesser extent.

This prior art practice is further illustrated by reference to the lubrication of'street railway journals or axles, particularly of those of 'steam andelectric street railways. In this field, oils of the viscosity of from 250 to 600" Saybolt at 100 F. are generally used. A further consideration in this and other analogous cases was the fact that the operating temperatures of the bearing or related mechanism under certain circumstances might be about 100 F. or even higher; with the result that the viscosity of the lubricant was chosen from the standpoint of such higher temperature operation. The variation in vis-' cosity of these prior art lubricants, which change in temperature over the usual operating range, was quite marked, so that when the' lubricant operated at the higher temperatures, it necessarily possessed a much higher viscosity at the lower temperatures.

requisite viscosity at the higher temperatures were actually solids at temperatures such as those frequently reached in this climate during the winter season.

The choice of heavy or viscous materials in accordance with such prior art practices, in order to secure adequate adhesiveness, result in a tremendous loss of power due to the internal friction of the lubricants. But these losses in power were either not recognized or appreciated in the prior art, or else were accepted as unavoidable.

Among the objects of thepresent invention is the production and use of lubricants of the lowest possible viscosity consistent withthe heat conditions under which they are to be used.

A further object of the invention is the utiliza- Y tion with such low viscosity lubricants of components added thereto for increasing the oiliness or adhesiveness of the low viscosity materials.

Still further objects of the present invention includethe incorporationinto the low viscosity lubricants of layer-forming components to insure the production of adequate lubricating oil films between the surfaces to be lubricated.

Other and further objects and advantages of the invention appear from the more detailed description set forth below, it being understood however that various changes within the scope of this invention may be made by those skilled in the art without departing from the spiritand scope of this invention'as herein disclosed.

And in fact in many'in stances, these lubricants in ordertogive the Accordingly in accordance with the present invention, the lubricant is preferably based on the utilization of hydrocarbon stock, such as that derived from petroleum andrelated oils, which hydrocarbon stock is of the lowestpossible 'vis- 5 cosity consistent with the heat conditions under which the lubricant isto be used, far lower than thatnormally employed for'the lubrication of. heavy machinery. While the lowest possible viscosity material is thus chosen, regard must be had for the flash point, fire test, andsimilar factors, where those factors are important. For example, in connection with the lubrication of internal combustion engines, the viscosity of the hydrocarbon stock would have to be. higher in order to secure the necessary flash point, etc.,

than would the lubricant used for the lubrication of an ice machine, where such factors would. be of little importance. In any event, in accordance with the present invention, the oil of lowest possible viscosity is'preferably chosen, having in mind the heat conditions under which-it is to be used. The use .of these low viscosity oils is advantageous, and particularly when full fluid or viscous friction is to be utilized, as the amount of friction under these conditions is dependent upon the viscosity only, and the lower the viscosity, the more economical is thelubrication. Further, the power losses due to the prior art use of heavylubricants is thus avoided. Now while the viscosity should be as low as possib e, the adhesive property should be as high as pomible in any of these given lubricants. When a bearing, for example, comes to a stop,

or when forany other reason,.the so-called-greasy nary petroleum oil was improved by the addition of saponiflable oil or fatty acids of saponiflable oil.

The principle on which an oily or greasy agent is added to the petroleum or other stock is based upon the fact that bearing surfaces by their sur face energy preferentially attract from the lubricant to themselves certain portions of the lubricant, and it has been found that theflrst layer of molecules so attracted may be held to the varying surfaces with great tenacity. gThis initial layer upon the surface is almost infinitely thin, and though useful is not sumciently thick to protect the metallic or other surface against rupture of 65 this thin oily film; which rupture though at portions only of the thin oily film, give rise'to undue friction and possible injury to the bearing surfaces. Further, the building up of the first layer involves a time interval that must be considered, and when the amount ofmaterial such as fatty acid, which is" readily absorbed by the ,bearing surface is present in the lubricant in small proportion only, the disturbancev created by the relative motion of the journal and bearing or other parts being lubricated may interfere with the formation or reformation of the first layer sufliciently to cause injury during the interval of its formation.

a which may be termed as a class, polar bodies.

Such added components for. increasing the oiliness or adhesiveness of the lubricant stock are compounds or mixtures of compounds containing a substituent group for which the surface forces of the metals have a particular attraction.

Now while as pointed out above, there is included with the low viscosity hydrocarbon stock, added components giving oiliness or greasiness properties, which components are used desirably in substantial amounts and will be exemplified below from a wide field of choice, such polar bodies form only a relatively thin layer-immediately adjacent to the metal surfaces, and it is desirable to place in-the stock a substance or substances to build up the initially formed thin layer into a relatively thick one to protect the surface against any possible injury during the interval when this primary layer is being formed, or at any time that this primary layer becomes ruptured. This may be done, for example, by 'addingsubstances which are attracted preferentially to the adsorbed primary layer or readily commingled with the substance or substances forming the primary layer. These additional layers, which are built up by such added substances may be called 'mush layers, and a lubricant which.has the property of building up these soecalled mush layers may be referred to as one having the property ofmushiness. These mush layers are more resistant the closer they are to the initial or adsorbed layer, and fade ofi gradually into the average composition of the lubricant. The total depth or thickness of the mush layer can be made within reason as great as requisite.

Accordingly the most desirable form of lubricant will be a compounded oil that possesses low viscosity, high adhesiveness, and'the ability to build up mush or protecting layers.

,In accordance with the present invention, there.

is accordingly used lubricating oil stock whether derived from petroleum or the products of distillation of coal and shale, which oil stock has the lowest possible viscosity for the conditions under which the machine operates; that is the lowest viscosity that is obtainable with requisite flash point to withstand the temperature prevalent during use. And this applies whether the lu-' bricant stock is derived from a straight paraffin stock, or from a so-called asphaltic or semi-asphaltic base oil. For cold conditions or climates the non-paraflln base oils have lower freezing points than the 'parafiin base oils, and are in general more desirable for this reason. 1

Low viscosity material for use in the lubrication of heavy-machinery, and having the requisite flash point, etc. was not available on the open market inspite of the wide variety of products produced by-thevari'ous oil companies and refineries. So that such low viscosity material had to be made for the first time and methods were developed for its production.

For example, a desirable stock may be made by distilling off about of the lighter material from kerosene oil, and using the remainder in the still as stock for the preparation of the finished lubricant. 'As a result of such distillation. the residue in the still is a product of requisite -fire point and cold test with much lower viscosity than that commercially available prior to the present invention. Products are thus produced having a viscosity of approximately from to at 100 F. as an upper limit.

Similar products of low viscosity may be prepared from the distillate of petroleum coal tar or shale oil in the range from which burning oils and not lubricants are generally prepared. These distillates I use as a base stock for special lubricants, as they can be secured with sufficiently high resistance to volatilization and low viscosity and are relatively slow to oxidize or sludge.

'Thus a specific product obtained by distilling ott 75% of ordinary coal oil tested as follows:

Similar products as to viscosity may be prepared from any of the other distillates of light boiling points, petroleum, coal tar or shale oil.

In general it may be stated that where flash point is an important consideration, the viscosity of the hydrocarbon stock should not be so low that the product has a fiash point of below about 225 to 230 F.; but as noted above, in connection with the more general considerations there given, these factors are variable depending upon the use to which the lubricant is to be put;

As indicative further of oils that may be used, products having the following characteristics may be noted:'

I n m Gravity at 60 F u. a 24. s Flash'point 0 1.. 290; can. 235 Fire point 0 r 340. 340. 265 Viscosity at 100 F. 12. 6o. 44

The products such as those indicated above are particularly desirably used in connection with the present invention. Further with materials hav- .no lower limit as to viscosity that can be employed. but oils running from 65" down as low as can be obtained, as probably around 35", may be utilized in accordance with the present invention.

The utilization of this low viscosity material as discussed above in the production or lubricants will, of course, depend on the particular machinery which is to be lubricated. In all cases, however, the lubricant produced in accordance with the present invention will utilize a hydrocarbon stock that is far lower in viscosity than was normally considered adequate for such work in the prior art. In general, it will be noted in accordance with the considerations given above that the spindle oils, as for example the first five oils of the Thompson tabulation above given, and having a viscosity at 100 F. of between 65 and 160 Saybolt, were limited for use on textile spindles where the load is practically zero and the speed is rather high. Such spindle oilshave nals where the prior art required hydrocarbon stock having a viscosity of between 250 to 600" Saybolt at 100 F., in'accordance with the present invention, a hydrocarbon stock will be employed having a viscosity less than 150-160" Saybolt at 100 F., and preferably with a viscosity of only about 100" Saybolt at 100 F.

But the invention is not limited to .the utilization of such low viscosity materials in connec tion with the lubrication of heavy machinery, since the invention may also be utilized in connection with improvements of the lubricants used for lubrication of spindles. Whereas in the prior art, as illustrated in the Thompson tabulation, the spindle oils employed have viscosities of about 65 to 160" Saybolt at 100 F., in accordance with the present invention it will be permissible to use oils of a much lower viscosity, suchas oils from 35 to 65" Saybolt at 100 F. when compounded with ingredients for increasing oiliness or adhesiveness, and/or materials which secure the protecting film referred to above.

Referring to the character of lubricants for use in internal combustion engines, such as automo bile engines particularly, several specific considerations may be noted. The useful work, i. e. energy delivered to the driving wheels of an automobile, is-only about. 18% of the total power developed. Most of the energy loss is in the cooling the friction is full fluid, but the character and thickness of the mush layer is evidently important. Other characteristics enter that need not be taken up in detail, such as character of decomposition under heat, kind of carbon formed in the cylinder, gumming deposits in the piston rings and valves, ease of combustion of residual deposits on cylinder walls, etc.

In general (for there are a few exceptions) the same oil is used for the lubrication of cylinders and bearings of the engine, as in an automobile. These latter operate, however, under very different conditions: first, the temperature is much lower during the major time of operation; second, the oil feed is superabundant; and third, the load on different parts of the bearing varies continually as the engine operates. The lubrication evidently is almost entirely of the full fluid type, and where an oilof the lowest possible viscosity is used economy is evident, but suflicient film-forming power to withstand squeezing" when the maximum load is applied is also necessary. This maximum evidently occurs during the time when the fuel is burnt '(exploded) in the cylinder. Throughout the whole mechanism the heavy load is applied only 25% of the time to the cylinders or bearings (except those which carry the crank shaft on which the load in pulsating but more nearly continuous).

Comparing now the viscosity of the oils in general use in internal combustion engines with those which will be employed in accordance with the present invention, the following table is given-it being understood, of course, that in all of the oils designated as Penniman oils or compounded oils made in. accordance with the present invention, they will include the materials necessary to build up the required protecting film, or to give the oiliness and adhesiveness characteristics rewater and waste gas which together total about quired in such compounded oils:

Extra light Light Medium Heavy 23g;

Viscosity at 100 (s. U i 115 2.50 400 650 1000 Kinematic viscosity... .36 .61 .83 1.36 2.05 Ponniman's Oil (8. U.)

Viscosity at 100 F 38 60 72 100 200 Kinematic viscosity i313 0942' 12 20 4 Power-Saving ii their'iction were full lluid" at 100 F- 9l% 81% 85% 86% 80% 70% of the total energy. The engine friction The-above figures of percentage saving are at loss is about 5.6% of the total energy and transmission friction losses are about 2.9% of the total energy developed. Disregarding the other losses, therefore, it is evident that if friction could be done away with entirely-which of course is impossible-the useful work done would be raised from 18 to 26.5%, or an increase of useful work of {7%.

The character of the lubricants used in internal combustion engines is of particular interest and importance. The machine in such cases from the lubrication standpoint may be considered from two standpoints-that of (a) the bearings and (b) the pistons. The piston lubrication requires an oil that will withstand a relatively high temperature, and it must adhere to thesurfaces of the cylinder and piston to secure a reasonable reduction 0f,frlct1on. The viscosity of the oil at temperatures varying from, say, 200 F. to 300 F. is evidently important as much of F. and change inversely with the temperature, for as the temperature increases the relative differences in viscosity become smaller, the film forming qualities also decrease.

Lubricants used in the transmission are in general the greases or heavy residual oils. The temperatures are comparatively low and the diiIerence between them and that of the surrounding air is due to friction only. On account of the way that gears engage, a small area at any one time is subject to a rolling squeezing action that renders an adherent mushy film advisable. The squeezing out 'of a high viscosity lubricant immediately before the high pressure moment is reached is evidently a'waste of power, which can only be lessened by using an oil of low viscosity, but this oil to be serviceable must have high mushiness", as well as the called oiliness. Theprior arttypes oflubricants used have had viscosities of about 800" Saybolt property commonly universal, or slightly below that. figure, which figure represents the minimum or lightest oil used. In accordance with the present invention, however, the compounded oils having viscosities in the range of that given above for lubrication of internal combustion engines and running up to a viscosity of about 2 00 to 250 will be utilized under to its maximum operating temperature, and are,

of course, greater until a heat balance is reached, and in very cold weather wherfflan economical heat balance is never reached, the economy effected is much greater.

While in someggses, as in turbines, and similar. machinery where the lubricant is pumped about a bearing by external means, the low viscosity stock may be utilized by itself for lubrication, its use in the ordinary bearing where no pumping action is present aside from that produced by the rotation of the bearing itself orthe joumal, is desirably carried out in conjunction with the added ingredient for improving the properties as to oiliness and mushiness.

The low viscosity oils, particularly of hydrocarbon stock character, are thus. desirably compounded with added ingredients for increasing their oiliness or adhesiveness, and their capacity to build up the so-called mush or protecting layers. As exemplary of the polar compounds that may be employed for increasing the 0111- ness and adhesiveness of these compositions, there may be mentioned fatty acids, particularly the higher fatty acids, such as for example, the fatty acids of castor oil, etc. The higher the fatty acid the better appears to be its eifect, and the presence of additional groups such as the hydroxyl group in the molecule with the carboxyl group appears to yield a better lubricant. The polar bodies are not limited to the fatty acids, but the non-fatty acid polar bodies, compounds or materials may be employed. The higher alcohols andketones are'advantag'eous and work almost as well as the fatty acids. sulphides and some of the metallic salts are also eflicient, though in general due to the ready availability of the fatty acids and their cheapness, they are more desirably employed. The higher alcohols and ketones may be readily obtained, for example from the oxidation products obtained during the air blowing of petroleum and related materials, particularly under pressure and at elevated temperatures, or from the residues remaining in the still during such air blowing processes. The sulphides may be prepared by direct treatment of petroleum oil with sulphur, the products being somewhat complex, but the polar bodies appear and their effect is available.

In those cases where the use of fatty acids may be objectionable due to the possible effectof such acids on the metal of the bearing or journal, the polar body may be chosen with such considerations in mind to avoid the presence of free acid groups of damaging characteristics.

The following method of preparing sulphur compounds for admixture with the oils in accordance with the present invention may be utilized where the oil may reach temperatures sulphur while agitating, for about two hours at 350 F. until the initial reactions are completed. The reactionstaking p ce are quite active and a good deal of, the sulphur is lost by volatllization. The temperature is then raised to.4 00 F. or hi er and kept at this temperature until the resulting composition will no longer darken a copper strip brought'in contact with it. The sulphur'base compound thus obtained is only slightly soluble in petroleum, and it is desirably utilized by compounding with from 50 to- 75% ofla saponiflable oil. From such resulting composition containing the saponiflable oil, from 2 to 15% of such composition is used in the petroleum or other hydrocarbon oils of the viscosities given herein.

The sulphur base compound acts asa polar compound and adheres tenaciously to the metallic surfaces of the metals, dragging with it considerable quantities of the saponiflable oil, and perhaps some of the constituents of the petroleum. Both adherence and thickness of film are secured in this way.

For the building up of the mush or protecting layers, various, substances are available. The best eflect is obtained with a material -that is soluble in the polar body and substantially insoluble in tho petroleum oil or hydrocarbon stock,

' so that when a portion of the fatty acid or other polar body adheres to the metal surface to form the primary layer, a very considerable quantity of the mush substance is withdrawn, and a thicker and more coherent mush layer built up. Saponifiable oils or fats that contain some fatty acid to act as the polar body serve in this connection. If the amount of fatty acid is small, the polar fatty acid will be withdrawn, and will act to take up but a comparatively small quantity of the mush ingredient, namely the neutral glycerides or fats, and a comparatively thin and soft coating results. The presence of comparatively large quantities of substances more attracted to the polar body will assist in building upa better mush layer. a

The ketones, and particularly complex mixtures of ketones as may be obtained from the heat treatment of the higher fatty acids may desirably be utilized as mushiness ingredients, although they also exhibitfoiliness" characteristics to a considerable extent. They may be prepared, for example, from the fatty acids, using iron as a catalyst, by heating until the condensation is effected. or the heating can be stopped when only a portion of the acid or acids have been con verted into ketones. Since the pure ketones are not very soluble in petroleum oil; it is generally better to use a mixture of fattyacids, such as are readily obtainable from cocoanut oil. When using the ketones and other substances formed in the way indicated, it is generally advisable to blend them with tallow, lard oil or other similar materials to improve the mushiness and for economical reasons, and to use such compositions of such ketones with tallow, lard oil, etc. for addition to the hydrocarbon stock material.

As a good example of materials to be used in building up the mush layer while also exhibiting the necessary polar properties, castor oil dissolved in oleic acid will serve, the castor oil being substantially insoluble in the petroleum oil stock used. Thus 2 parts of castor oil to 1 part of oleic acid may be employed. The oleic acid acting as the polar body carries.down with it large quanti ties of the castor oil and the mush layer con-' sists largely of oleic acid and. castor oil. This artificial or synthetic composition builds up a better able for use in accordance with the present inv vention. Any method by which molecular attraction, i. e., the clinging together of molecules by either known chemical attraction or residual chemical forces, may be made use of. It is well known that substances used in lubrication build up a surface film on the metallic surface of considerable tenacity. Other substances may also form or build up such films, but they are. not'of value as lubricants.- In those cases where the.

fatty acids are objectionable in the lubricant, the substituted ammonias that have little value as lubricants but build up films on the surface can be used. If there is also added some material of high lubrication power that is selectively absorbed by the substituted ammonia, or which forms molecular aggregates with it, a satisfactory result is secured. Inthe lubrication of internal combustion engines, where high temperatures prevail,

- the avoidance of such-acidity is desirable. In such cases, there may be employed a mixture, for example, of diphenylamine and tallow oil (the latter containing little or no free acid). Good results are obtained when only 5% of this mixture is added to-the selected petroleum stock. I

Soaps which form an emulsion with the petroleum stock, or which are soluble ,in the petroleum stock can also be used. For example,

soaps with petroleum stock, particularly the soda and lime soaps that are present as colloids.

The soaps that go into solution include lead oleate, copper oleate, and the oleates of the heavy metals generally. the alkalies and alkaline earth metals forming colloids. As apparently soluble compounds, there may be mentioned copper oleate, zinc oleate and sodium sulphur oleate, while ordinary calcium and sodium oleate when used are present as colloi ds.

Animal oils, such as lard oil, may be used, in amounts as exemplified by 10%, but other oils, such as tallow oil.which contains some free acid is preferable to lard oil, and castor oil when in solution as illustrated above is superior to either lard oil or tallow oil.

In some cases, the body added to improve the mushiness characteristic may at the same time possess a polar property, so that in this way two purposes can be secured at the same time. This is particularly true of some of the sulphur compounds in the nature'of sulphides illustrated above, as well as with the class of compounds known as sulphonic acids. As exemplary of the sulphonic acids that may be used for this purpose, the following is given.

Sulphonic acids derived from the treatment of unsaturated petroleum compounds, that is to say those obtained from the residue of the purification of ordinary petroleum oil bytreatment with sulphuric acid are available for present purposes. These sulphonic bodiesare of indefinite chemical composition. The sulphonic acid group H80: in these bodies acts as the polar body.- Sulphonic acids can also be prepared and used which are dyestuff intermediates, and these compounds may be very complex or elaborate. The simple bydrocarbons and the more complex ring compounds including doubleand triple rings may serve in this connection for the production of lead has also proved these sulphonic derivatives. As an example of dyestuff intermediates utilizable in this connection mention may be made of the naphthol sulphonic acids.

These bodies which serve as both the polar and the mushiness ingredients may of course be used as the polaringredient alone, and in general it has been found more desirable to-use two separate ingredients for this purpose rather than to attempt to accomplish both ends with a single substance.

Further it may be noted that when high temperatures avail in use, the oils have a tendency to oxidize rather readily with the formation of gummy materials that are disadvantageous in practice. Some of the animal and vegetable oils and their derivatives used as the greasy or oiliness components oxidize less readily than others, but all of them even when mixed with mineral oils oxidize to a greater or lesser extent, and some like cottonseed oil and corn oil are seldom or never used either alone or mixed with mineral oil on account of this ease of oxidation. To prevent such oxidation, substances may be introduced into the lubricant composition that lessen or prevent the oxidation of oil undergiven conditions of service, so that 'undesirable changes in the oil due to oxidation rendering them undesirable from many points of view are avoided or eliminated entirely. The use of anti-oxidants evidently broadens the field in use of vegetable oils and mineral 0ils; as mineral oils also oxidize to a' lesser extent than the vegetable and animal oils.' The anti-oxidant may beany substance that in a general sense reduces the eflect of oxidation or air upon the lubricant. As such, there may bementioned tetraethyl lead, phenol disulphide, amino and amide compounds, phenols, such as pr'rogallol, hydroquinone, and other substances such as elementary sulphur, malachite green. The amountof the anti-oxidant is varied according to the time at which the lubricant is .to be used, and the conditions as to oxidation. At a very low temperature, the eifect of the oxygen is very little feared, so that the amount of antioxidant used in such cases, may be as low as .l%.

The dinaphthylamine is desirable, but tetraethyl to be moderately eflicient. The amounts of the components added to inorease oiliness or adhesiveness,'and to build up the mush or protecting layers, may-vary within substantial limits, such as up to 15%, although more than 10% will generally not be required. Lesser amounts can,-of course, be utilized. The amounts of such added components should not materially or substantially affect the viscosity of the hydrocarbon stock, or of the final composition, and at least should not carry the viscosity beyond the point desired for the particular purposes for which the lubricant is designed.

The following specific example of a lubricant made in accordance with the present invention and utilized in connection with the lubrication of street railway journals, and which has proved particularly advantageous in such practice is given.

2 parts of castor oil are dissolved in commercial oleic acid, and the mixture heated to about F. to insure solution. The resultant product is admixed or added to petroleum stock having the characteristics set forth above, the castor oil, oleic acid mixture constituting 5% of the total admixture. When used at a relatively e evated temperature, 1 part of beta beta dinaphthylamine is added to the oil as an anti-oxidant; while adding of lard oil, for example, to the hydrocarbon stock material described above and In one case, for example, utilizing a low viscosity numbered I, II and III.

As exemplary of the phenomenal results flowing from the present invention, attention may be called to the fact that it has been appliedin the lubrication of a large railway system where about 30,000 bearings were under study. Whereas it has been the custom to use oils of viscosity of about 250" viscosity Saybolt on such railway system prior to ,the development of the present invention, in accordance with the present invention, the lubrication of bearings on that street railway system is now being madewith oils of. a viscosity of 35" Saybolt at 100 F. Lubrication by means of these low viscosity oils in accordance with the present inventionv has resulted approximately in a reduction in power costs ofabout 20% annually. Comparable results have been obtained in connection with the lubrication of internal combustion engines, such as automobile engines.

oil lubricant in accordance with the present invention the horsepower developed was 171i; as

compared with 14.2 utilizing the ordinary automobile oil oi the prior art. And in addition, by the utilization of the low viscosity oil, not only was there the phenomenal increase in horsepower referred to above, but the gasoline consumption was reduced about 33%, even though the horsepower developed was as markedly great as that noted above.

- 200" Saybolt.

2.. A method of lubricating internal ,combustion engines such as automobile engines which comprises utilizing therein a lubricating oil containing a hydrocarbon oil having a viscosity within the range 135" to 250" Saybolt" at 100 F. and substantially less than that normally used 'for lubrication of automobile engines, and a component for increasing the oiliness of the,-

. composition and a mushiness component, the

oiliness and mushiness components not increas-- ing the viscosity substantially beyond 250" Saybolt.

3; A lubricating oil for internal combustion engines, said oil containing a hydrocarbon oil having .a viscosity above 135" and below 250" Saybolt at 100 F. and a component for increasing the oiliness of the compositionwithout substantially increasing the viscosity beyond 250" Saybolt.

4. A lubricating oil for internal combustion engines, said oil containing a hydrocarbon oil having a viscosity within the range 135" to 250" Saybolt, but substantially lessthan that normal-- ly used for lubrication of internal combustion engines, and a component for increasing the oiliness of the composition and a. mushiness component, the oiliness and mushiness components not increasing the viscosity substantially beyond 250"- Saybolt.

5. A lubricating oil for internal. combustion engines, said oil containing a hydrocarbon ,oil

having afviscosity within the range of 135 to 200" Saybolt at 100 F., and having a flash point nal combustion engines, a component for increasing the oiliness of the composition, and a mushiness component, the oiliness and mushiness components together not exceeding about 15% of the final composition and not increasing the viscosity substantially beyond 200" Say-' bolt.

7. A lubricating oil for internal combustion engines, said oil containing a hydrocarbon oil having a viscosity Within the range of 135 to 200" Saybolt at 100 F. and a component including tallow oil and diphenylamine for increasing the oiliness of'the composition without.

substantially increasing the viscosity beyond 200 Saybolt, the tallow oil and diphenylamine together constituting not substantially more than 5% of the composition.

not substantially below 225 FL, and a compothan that normally used for lubrication of inter- 8. A lubricating oil for internal combustion engines, said oil containing a hydrocarbon oil having a viscosity within the range of 135 to 200 Saybolt at 100 F., and a component for increasing the oiliness of the composition without substantially increasing the viscosity beyond 200" Saybolt, said component including sulphurized tallow oil and a saponifiable oil, the sulphurized' tallow oiland 'saponifiable' oil together constituting between 2 to 15% of the composition.

9. A lubricating oil for internal combustion engines, said oil-containing a hydrocarbon oil having a viscosity within. the range of 135 to 200" Saybolt at 100 F.,'and a component for increasing the oiliness ofthe' composition withthan 15%-of the composition.

. WILLIAM B. 'D. PENNQIMAN.

a and ketone constituting'not substantially more H 

